Roller reamer stabilizer

ABSTRACT

A roller reamer stabilizer the bearings of which are lubricated by air bleed from the centre core of the drill string. The roller cutters are mounted in recesses in the body such that the roller cutters are free to rotate about their bearing pins in suitable journal bearing blocks. The bearing blocks are provided with passage means from the centre bore of the drill string to provide the said air lubrication. The air also serves as a cushion between the roller and the bearings.

United States Patent 1191 White June 28, 1974 [54] ROLLER REAMERSTABILIZER 1,812,044 6/1931 Grant 175/346 X 1,938,246 I2 1933 Carlson .1175/346 X [75] Inventor: Kenneth Calgary 2,122.763 7/1938 Smith 175/346Alberta, Canada 2,670,046 2/1954 Kinzbach 7. 175/346 x AssigneeZ westernDysart X 4 Limited, Calgary, Alberta, Canada [22] FiledZ Man 12, 1973Primary Examiner-David H. Brown [2]] Appl. No.: 340,250

[57] ABSTRACT A [30] Foreign pphcauon Prlomy Data A roller reamerstabilizer the bearings of which are lu- DCC. 29, Canada bricated airleed om th Centre o e of t e string. The roller cutters are mounted inrecesses in 2? 3533 the body such that the roller cutters are free torotate i h 75/337 5 324F348 about their bearing pins in suitable journalbearing l 0 an 175/354 blocks. The bearing blocks are provided withpassage means from the centre bore of the drill string to pro- 56 R f dvide the said air lubrication. The air also serves as a 1 UNITE]; 52:23;:ZTENTS cushion between the roller and the bearings.

1,139,529 5/l9l5 Hughes 175/345 X 6 Claims, 6 Drawing FiguresPATENIEDJUNZB m I SHEET 1 BF- 2 8 v p q \r O O O 0 50 O D O 0 O J 0 0 CO C m 2 VMLI 4 5 r llllll ll 000 O f L llllll oo o 0 6 9 F/GZ ROLLERREAMER STABILIZER BACKGROUND OF THE INVENTION having a balanced lifesuch that the body of the unit 1 matches the life of the roller cutters.It has, however, been found that the units presently in use suffer frompremature end wear on the rollers and loosening of their axle shafts.

Expendible roller reamers are generally of two piece construction havinga box thread end for attaching the rock bit and a pin thread end forconnection to the drill string. The two pieces are connected by pins asin US. Pat. No. 3,306,379 granted to Joseph A. Kloesel, Jr., et al., onFeb. 28, 1967, or by welding. This welded unit generally has thecircumferential weld just above the upper end of the axle shaft, suchthat the lower or box portion of the reamer body has pre-cast recessesfor the reamer cutters. The axle shafts are press or shrunk fit into thecast body.

Due to radial impact loads on the reamer cutters, the axle shaft of theexpendible reamers tend to loosen such that the axle rotates in thereamer body causing the air lubrication supply hole to be blocked. Thereis then a rapid heating of the hardened axles and cutter bearingsurfaces causing softening such that the abrasion and wear resistance ofthese components is significantly shortened.

Size limitations and radial loading dictate the amount of spaceavailable for the axial thrust on the rollers. The top end of therollers from field tests show less wear than the bottom end, which wouldsuggest that the rol ler is helddown by its own weight more than it isresisting axial loads as would be encountered in entering an undergaugehole. The abrasion encountered in drilling and the downward weight ofthe roller is significant enough to cause rapid wear of the rollercutter bottom face and in some instances one-quarter of the roller isgone before the body is appreciably worn.

BRIEF DESCRIPTION OF THE INVENTION The present invention overcomes theproblem of roller thrust face wear and loosening of the axle shafts inthe body while still maintaining an economical cost balance to make thereamer an expendible item.

For economical reasons, the body of the reamer is preferably an abrasionresistant steel casing having recesses provided for the roller cuttersand bearing blocks. The rollers and axle pins become an integral unithaving a larger diameter with annual rows of tungsten carbide insertsand two smaller diameters at each end intended to form bearing pins. Thebearing pins have a primary thrust face at their outer axialextremities. The bearing. pins are slightly longer than the journal inthe bearing block, and there is thus a gap or space between thetransitionary plane adjoining the bearing pin on the roller with thelarger diameter having the tungsten carbide inserts. The gap is formedbetween the secondary thrust faces on the roller and the bearing block.

Specific preferred embodiments and innovative features of the inventionwill now be described with reference to the following drawings, inwhich,

FIG. 1 illustrates the general configuration of a roller reamerstabilizer according to the invention;

FIG. 2 illustrates an assembled roller and bearing block combination,partially in section prior to mountmg;

FIG. 3 illustrates a centerline section along line 3-3 0 of FIG. 2;

FIG. 4 is a cross-section of a bearing block modifica tion incorporatinga bearing sleeve and separate thrust button;

FIG. 5 is an end view of the thrust button shown in FIG. 4; and

FIG. 6 is a cross-section along line 6-6 of the thrust button shown inFIG. 5.

DESCRIPTION WITH REFERENCE TO THE DRAWINGS Referring to FIG. l, thereamer body I is provided with a pin end 2 threaded for releasableattachment to the drill string and a box end 3 for attachment to thedrill bit. Bearing blocks 4 and 5 are attached by welding 6 to thereamer body 1. The roller cutter 7 is provided with tungsten carbideinserts as shown 8. Recesses 9 are provided in the body 1 for threeroller cutters like 7 such that they are at to one another and are freeto rotate.

The assembled roller and block combination shown in FIG. 2 illustratesthe gap 10 between the secondary thrust face 11 on the bearing block 13and the roller 7. This gap is approximately 1/64 inch in the newcondition. The sectioned block 13 shows the primary thrust face 14 onthe block mating with the primary thrust face 15 on the roller 7. Theprimary thrust face 15 on the roller cutter pin 7 is an integral part ofthe pin and is formed with an angled end such as would be formed by thedrill utilized in drilling the bearing pin hole in the block. It istherefore preferred that the primary thrust face on the roller cutterbearing pin have a total subtended angle of approximately 120. A furtheradvantage of forming this angled thrust face is that when the bearingsare worn the roller will centralize itself on the sloping primary thrustfaces and minimize the sliding and rolling contact of the bearing pin ofthe roller cutter in the journal formed in the block.

The annular rows of tungsten carbide inserts 8 are preferablysymmetrical about the midpoint in the roller cutter such that the rollercan be turned end for end in the recess in the body. It is furtherpreferred that the end annular rows of inserts 16, 17, 18, and 19contain 9 inserts per row and that row 17 be offset 20 from row 16 androw 19 be offset 20 from row 18. The intermediate rows of insertspreferably contain 6 inserts per row and are offset 30 from row to row.

Air lubrication is provided for each bearing pin on the roller cutterthrough hole 20 as shown in FIG. 3. A corresponding hole is drilled intothe center annulus of the reamer body to bleed enough air therefrom tokeep the bearing surfaces and thrust faces free from foreign materials.Air lubrication hole 20 in the bearing block should be drilled such thatits termination is approximately at the apex of 120 primary thrust faceas shown in the sectioned block of FIGS. 2 and 3. Drilling of hole 20 inthe aforementioned position tends to create a cushion of air between theprimary thrust faces such that there is a shock absorbing effect whenthe roller cutter is subjected to axial movement. The preferred holesize is inch in diameter in the block and /4 inch in diameter in thereamer body.

FIG. 4 illustrates a bearing block having a wear resistant sleeve 21either press or shrunk fit into the bearing block body. There is afurther modification in that the primary thrust face 22 is flat and is aseparate portion of the bearing rather than part of the bearing block.The thrust button 23 has the primary thrust face 22 carburized andhardened. The use of a bearing sleeve 21 and thrust button 23 as shownin FIG. 4 eliminate carburizing and hardening of the bearing surfaces aswould be required in a block of the type shown in FIGS. 2 and 3 butmanufacturing costs tend to be somewhat higher.

Referring to FIGS. and 6, air lubrication is provided through relievedareas 24 and 25 to the primary thrust face by hole 26. Relieved area 24is sized such that when thrust button 23 is installed in a blockaccording to FIG. 4 air passageway 27 is not blocked and air from thecenter annulus of the tool body is directed on to the center of theroller cutter bearing pin through the aforementioned passageways andrelieved areas.

What I claim as my invention is:

l. A roller reamer adapted for releasable attachment to a tubular drillstring in which air flows through a center bore and drill bit cuttingsare removed up an annular space between the rock bore and the drillstring, said roller reamer having a tubular body with a plurality ofroller cutters mounted in recesses in said body such that said rollercutters are free to rotate about integral bearing pins in suitablejournal bearing blocks. said journal bearing blocks being provided withair passage means from the center bore to provide air lubrication to thejournal and bearing pin surfaces.

2. A roller reamer according to claim I in which said roller cuttershave a major diameter provided with annular rows of tungsten carbideinserts and two minor diameters forming bearing surfaces, said major andminor diameters being joined by a transitionary surface substantiallyperpendicular to the longitudinal axis of the reamer and saidtransitionary surface fonning a secondary thrust face.

3. A roller reamer according to claim 1 in which said roller cutterbearing pins have at their outer longitudinal extremities a primarythrust face.

4. A roller reamer according to claim 3 in which the air passage meansin said journal bearing blocks are disposed so that air may be bled fromthe center bore to the primary thrust faces on the roller cutter bearingpins.

5. A roller reamer roller cutter according to claim 3 in which theprimary thrust face is provided with self centering means consisting ofa convex conical primary thrust face mating with a concave conicalthrust face in said journal bearing block.

6. A roller reamer having journal bearing blocks according to claim 4 inwhich said air lubrication passageway provided terminates substantiallyat the apex of said concave conical thrust face.

1. A roller reamer adapted for releasable attachment to a tubular drillstring in which air flows through a center bore and drill bit cuttingsare removed up an annular space between the rock bore and the drillstring, said roller reamer having a tubular body with a plurality ofroller cutters mounted in recesses in said body such that said rollercutters are free to rotate about integral bearing pins in suitablejournal bearing blocks, said journal bearing blocks being provided withair passage means from the center bore to provide air lubrication to thejournal and bearing pin surfaces.
 2. A roller reamer according to claim1 in which said roller cutters have a major diameter provided withannular rows of tungsten carbide inserts and two minor diameters formingbearing surfaces, said major and minor diameters being joined by atransitionary surface substantially perpendicular to the longitudinalaxis of the reamer and said transitionary surface forming a secondarythrust face.
 3. A roller reamer according to claim 1 in which saidroller cutter bearing pins have at their outer longitudinal extremitiesa primary thrust face.
 4. A roller reamer according to claim 3 in whichthe air passage means in said journal bearing blocks are disposed sothat air may be bled from the center bore to the primary thrust faces onthe roller cutter bearing pins.
 5. A roller reamer roller cutteraccording to claim 3 in which the primary thrust face is provided withself centering means consisting of a convex conical primary thrust facemating with a concave conical thrust face in said journal bearing block.6. A roller reamer having journal bearing blocks according to claim 4 inwhich said air lubrication passageway provided terminates substantiallyat the apex of said concave conical thrust face.